by Fredreka Schouten, USA TODAY

by Fredreka Schouten, USA TODAY

WASHINGTON - A conservative group backed by billionaire brothers Charles and David Koch will launch a new round of advertising Thursday to attack President Obama's health care law, less than two weeks before enrollment opens for new health care exchanges.

Americans for Prosperity will spend $3.1 million advertising in six states, said President Tim Phillips. Its 60-second ad stars an older woman who said she has twice survived cancer and frets about government interference in a medical system that she says has saved her life.

The commercial will run in Ohio and Virginia - both presidential swing states - along with North Carolina, Alaska, Louisiana and Arkansas, all home to Democratic senators who are top GOP targets in next year's elections. The ad will run through Oct. 2.

The advertising is part of a persistent GOP-led push to sow doubts about Obama's leadership and the 2010 health care law that is his signature legislative achievement. A USA TODAY/Pew Poll released this week shows 53% of those surveyed disapproved of the law, and 41% said it would have a "mostly negative" effect on them and their families in the coming years. Only 25% predicted mostly positive results.

Foes of the Affordable Care Act have run nearly five times the number of TV commercials in recent months as its proponents have aired, a new advertising analysis shows.

Between July 1 and Sept. 16, Americans for Prosperity led all advertising, running more than 3,200 spots to slam the law, according to a tally of advertising by Kantar Media.

That's four times the number of ads placed in the same period by the U.S. Department of Health and Human Services, charged with implementing the law, Kantar's estimates show.

"Opponents have turned this into their primary club in their campaign to batter the president," said Elizabeth Wilnervice president of Kantar's Campaign Media Analysis Group. "The Republican mantra has become: less taxes, more jobs and Obamacare sucks."

The law faces its biggest test Oct. 1 when enrollment opens for the new online marketplaces, known as exchanges.

Under the law, most Americans without health insurance must buy coverage through the exchanges or pay a fine. The administration hopes to sign up 7 million uninsured Americans in the program's first year. The law's success relies, in part, on persuading the young and healthy to enroll to balance the costs of those with chronic conditions.

Phillips said his group is working for the law's eventual repeal. "We want to keep this issue at the forefront," he said.

Conservatives also have used the issue to energize their voting base. Though the spending is relatively small at this point, advertising about the Affordable Care Act already has begun to crop up in next year's midterm elections for Congress, Kantar's data show. Kentuckians for Strong Leadership, a super PAC supporting Senate Minority Leader Mitch McConnell's re-election, recently included the health care law in its ad targeting McConnell's leading Democratic challenger, Kentucky Secretary of State Alison Lundergan Grimes.

Proponents, meanwhile, say they plan to ramp up spending. HHS is planning its own advertising campaign in the fall, but has not released specifics.

"We will continue educating and informing the uninsured," agency spokeswoman Joanne Peters said in an e-mail.

Dan Mendelson, who oversaw outreach for the children's health insurance program in the 1990s during the Clinton administration, said the Obama administration's publicity efforts to date have been "tepid," but said it's hard to sell insurance plans that aren't yet available.

Once the enrollment opens on Oct. 1, Americans will see even more advertising from insurance companies touting their services before enrollment ends on March 31, 2014, he said.

"This law has been a political football for a long time," said Mendelson, now CEO of consulting firm Avalere Health. "As of Oct. 1, it will become a commercial insurance offering."

Proponents say they are confident consumers will respond to nuts-and-bolts information about health insurance and tune out the political spin.

Enroll America, a non-profit group run by former White House official Ann Filipic that is encouraging Americans to shop for insurance in new online marketplaces, is doing no traditional television advertising. Instead, it plans digital advertising to target uninsured individuals through social media and online sites, said spokeswoman Jessica Barba Brown.

It also has started a massive outreach campaign, deploying 127 staffers to 10 states that have not established their own health care exchanges. An estimated 3,000 volunteers have been recruited to help knock on doors, staff phone banks and pass out health care literature at an array of gathering places, from farmer's markets to churches.

Enroll America plans to spend "tens of millions of dollars" on the effort, Brown said.

"This is about to become real for people and that's what we are focusing our energy on," she said. "We want to make sure we can connect people with the care they need."